1288921 has 2 divisors, whose sum is σ = 1288922. Its totient is φ = 1288920.

The previous prime is 1288919. The next prime is 1288933. The reversal of 1288921 is 1298821.

It is a happy number.

It is a weak prime.

It can be written as a sum of positive squares in only one way, i.e., 741321 + 547600 = 861^2 + 740^2 .

It is a cyclic number.

It is not a de Polignac number, because 1288921 - 2¹ = 1288919 is a prime.

It is a super-2 number, since 2×1288921² = 3322634688482, which contains 22 as substring.

Together with 1288919, it forms a pair of twin primes.

It is not a weakly prime, because it can be changed into another prime (1288951) by changing a digit.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 644460 + 644461.

It is an arithmetic number, because the mean of its divisors is an integer number (644461).

2^1288921 is an apocalyptic number.

It is an amenable number.

1288921 is a deficient number, since it is larger than the sum of its proper divisors (1).

1288921 is an equidigital number, since it uses as much as digits as its factorization.

1288921 is an evil number, because the sum of its binary digits is even.

The product of its digits is 2304, while the sum is 31.

The square root of 1288921 is about 1135.3065665273. The cubic root of 1288921 is about 108.8283638294.

It can be divided in two parts, 1288 and 921, that added together give a square (2209 = 47²).

The spelling of 1288921 in words is "one million, two hundred eighty-eight thousand, nine hundred twenty-one".